FAQs - Historic Earthquakes and Statistics
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Q: Where do earthquakes occur?
A: Earthquakes can strike any location at any time. But history shows they occur in the same general patterns year after year, principally in three large zones of the earth. The world's greatest earthquake belt, the circum-Pacific seismic belt, is found along the rim of the Pacific Ocean, where about 81 percent of the world's largest earthquakes occur. It has earned the nickname "Ring of Fire". The belt extends from Chile, northward along the South American coast through Central America, Mexico, the West Coast of the United States, and the southern part of Alaska, through the Aleutian Islands to Japan, the Philippine Islands, New Guinea, the island groups of the Southwest Pacific, and to New Zealand. This earthquake belt was responsible for 70,000 deaths in Peru in May 1970, and 65 deaths and a billion dollars' damage in California in February 1971.
Why do so many earthquakes originate in this belt? This is a region of young, growing mountains and deep ocean trenches which invariably parallel mountain chains. Earthquakes necessarily accompany elevation changes in mountains, the higher part of the earth's crust, and changes in the ocean trenches, the lower part.
The second important belt, the Alpide, extends from Java to Sumatra through the Himalayas, the Mediterranean, and out into the Atlantic. This belt accounts for about 17 percent of the world's largest earthquakes, including some of the most destructive, such as the Iran shock that took 11,000 lives in August 1968, and the Turkey tremors in March 1970 and May 1971 that each killed over 1,000. All were near magnitude 7 on the Richter scale.
The third prominent belt follows the submerged mid-Atlantic Ridge.
The remaining shocks are scattered in various areas of the world. Earthquakes in these prominent seismic zones are taken for granted, but damaging shocks occur occasionally outside these areas. Examples in the United States are New Madrid, Missouri, and Charleston, South Carolina. Many years, however, usually elapse between such destructive shocks.
